Vehicular communications systems

ABSTRACT

This invention consists of a waveguide of substantially trapezoidal cross section, having at its smaller end a closed base portion, surrounding a conductor spaced therefrom, and exteding therefrom a gradually widening top portion open at its outer end to permit the wave propagated along the wave guide to emerge therefrom into a space adjoining said top portion.

Unite States Hafner 1 May 1,1973

[54] VEHICULAR COMMUNICATIONS SYSTEMS [76] Inventor: Theodore Hefner,1501 Broadway,

New York, N.Y. 10036 22 Filed: Mai-.24, 1971 211 Appl.No.: 127,588

[52] US. Cl ..343/717, 343/786, 333/84 R [51] Int. Cl. ..H0lq 1/32 [58]Field of Search .L ..343/71 1, 712, 713,

[56] References Cited UNITED STATES PATENTS 10/1970 l-lafner ..333/95 S6/1971 Nakahara et a1. ..343/713 3,609,675 9/1971 Abele ..343/7l3FOREIGN PATENTS OR APPLICATlONS 1,163,386 9/1969 Great Britain ..333/84L Primary Examiner Eli Lieberman Att0rney-Theodore Hafner [57] ABSTRACTThis invention consists of a waveguide of substantially trapezoidalcross section, having at its smaller end a closed base portion,surrounding a conductor spaced therefrom, and exteding therefrom agradually widening top portion open at its outer end to permit the wavepropagated along the wave guide to emerge therefrom into a spaceadjoining said top portion.

8 Claims, 6 Drawing Figures Patented May 1, 1973 FIG. 2.

INVENTOR THEODORE HAFNER VEHICULAR COMMUNICATIONS SYSTEMS One of theobjects of this invention is to permit the coupling of a vehicularcommunications system with a stationary transmission line, with aminimum of loss and a minimum of radiation.

Another object ofthe invention is to provide a transmission line of lowloss and broad bandwidth, and yet of minimum dimensions so as to besupportable in relatively restricted areas such as provided in the spacebetween train and ground or side walls.

Still another object of the invention is to provide an efficientcoupling between transmission line andvehicle, or the pickup mountedthereon, for minimum radiation, and if possible, for operation withoutrequiring F.C.C. frequency allocations.

These and other objects of the invention will be more apparent from thedrawings annexed herein, in which FIG. 1 represents in cross section atransmission line embodying certain principles of the invention;

FIG. 2 gives an example of the mounting of a transmission line,underneath the guide way of train or another type of vehicle, in a crosssection perpendicular to the longitudinal extension of such guide way.

FIG. 3 illustrates a method of assembly in the field.

FIG. 4 illustrates an arrangement for measurement the electricalproperties of a transmission line such as illustrated in FIG. I or FIG.2.

FIG. 5 shows schematically another type of testing arrangement.

FIG. 6 shows the arrangement of FIG. 4 in cross sec tion.

As indicated in FIG. 1, the transmission line according to theinvention, may consist of an aluminum or other type of conducting trough1, shown in FIG. 1 in a cross section perpendicular to its longitudinalextension, comprising a square to preferably quadratic portion 2 closedat one end, open at the other end, from which extends, preferably of onepiece with each other, an expanding trapezoidal portion open at itsouter end, and schematically indicated at 3.

The dimensions of the transmission line are wave length depending,preferably of the order of not more than 20 percent of the operatingwave length for its length dimensions, and, not more than percent forits width dimensions In the present example, the lower square portion ofthe cross section is of the order of 10x10 cm, while the trapezoidalportion extendion at an angle of about 30 to a length of about em; allthese dimensions being provided for'an operating wave length of theorder of 1.5 m. The square portion 2 of the cross section of thetransmission line supports a conductor 4, preferably in a centralposition with respect to the sides of portion 1, and also coated with adielectric as schematically indicated at 5. Conductor 4 may consist ofcopper tubing, and coating 5 of preferably pure polyethylene. Thediameter of the conductor 4 is of the order of 10 percent of thecrosssectional dimensions of square portion 2, while its coating 5 has athickness of the order of 50 percent of the radius of copper conductor4, which is of the order of l /2 inch in this specific example of theinvention.

Coated conductor 4 should be as light as possible so as to permit a safeand accurate support in the center of portion 1. In the particularexample of FIG. I, the coated conductor 4 is supported on styrofoam withwhich the square portion 2 of the cross section of the line is filledout, and which is schematically indicated at 6, and serves apart fromsupporting conductor 4, to define losses of the line to a minimum value.

As illustrated in FIG. 2, and for a particular application of theinvention, also shown in cross section, the transmission lineschematically indicated at 7, appears mounted beneath a concrete slabschematically indicated at 8, and attached to such slab by hangers (notshown) or in any other way as required by the mechanical specificationsof the entire structure. In the particular example shown, the length ofcross section of line 7 (ie its extension in the direction of longestdimension of the crosssection) corresponds approximately to the width ofthe overlaying slab 8 which will permit the field emerging from theinside of the wave guide to expand freely with a minimum of loss, andalso to be picked up unimpeded by a dipole or any other pickup suitablefor this purpose as schematically indicated in FIG. 2 at 9, andextending substantially in a plane sub stantially perpendicular to theplane formed by the outer opening 10' of the trapezoidal portion 10.

Slab 8 is shown supported on a steel girder 11, forming on its uppersurface the guide way for the rubber wheels 12 of a vehicle (not shown)carrying on its understructure, in a manner also not shown, the pickupor coupling 9.

Exact dimensions of rails and other parts of this structure, also of anybrackets for the tracks which may be required at curves, must be such asto permit safely maximum movements of the vehicle in horizontal andvertical directions, even in the case one or both of the rubber wheelsshould become deflated thus causing rather considerable deviations fromnormal movement tolerances.

The installation of the wave guide can be effected in a rather simplemanner, by starting from a flat aluminum sheet, provided if necessarywith longitudinal indentations corresponding to the various cornersshown in the cross section of FIG. 1. In this case, duringtransportation, the waveguide will be carried wound up on a large reelschematically indicated in FIG. 3 at 13 from which the flat, butidentured strip 14 is rolled off, over or close to the part of the trackto which it is to be attached. During the rolling-off operation, strip14 is being shaped, by being guided for example, over three shapingrollers, one arranged on top of sheet at 15, the other two underneath,at l6, 16', from which, along indentures l3, emerges 17, the trapezoidalform indicated in FIG. I in cross section.

Thereafter, the trapezoidally shaped strip 17 is attached to theguideway as for example indicated in FIG. 2. In a subsequent operation,the preformed poystyrene foam shape 18 which has been provided duringmanufacture with a slot 19 to permit insertion of the coated conductoris inserted into installed aluminum trough as indicated at 20, andthereafter the conductor is inserted through slot 19 which is so shapedthat it does permit insertion, but also positioning of the conductorinside the foam 18.

In order further assure the rigidity of the structure, the top surfaceof foam shape 18 may be covered with a weather resistant coating orcover as schematically indicated at 21 which should also be designed tohave as little effect as possible on the characteristic or loss of thewave emerging from the line; thus while it may contain weather resistantcarbon or any other weather resisting component, it should be made asthin as possible to reduce loss to a minimum.

A preferred method and arrangement for testing: the new waveguide underlaboratory conditions is apparent from FIG. 4, wherein for an operatingwave length of 1.50 in, two guide sections each of 1.50 m length, arearranged at 22, 22' respectively each section between two conducting endplates schematically indicated in FIG. 4 at 23, 24, and 25, 26,respectively. In one of these sections, for example 22, the conductor isprovided with a dielectric sheet, while in the other, for example 22',such dielectric sheet is omitted to evaluate the best conditions for apredetermined frequency range. Another change is to replace or removethe dielectric 6 supporting the conductor; the latter may then besupported on V-shaped loops.

Now the two structures as shown in FIG. 4 are investigated for loss andany other proerties, at a number of reasonable frequencies, suchapproximately 100 Mhz, 200 Mhz, 300 Mhz, and 500 Mhz.

More specifically, the resonant curves i.e., the Q of the resonatorallows determination of the transmission loss under more or less idealconditions.

In a subsequent phase of measurement, concrete blocks are approached tothe guide, and the effect on the Q is being determined. This shouldyield a fair estimate of the actual guide when it is installed in thefield.

If results indicate that the dimensions could be reduced, themeasurements as above are to be repeated with a modified cross section.

In a second test series, provided the first outlined above, isconsidered successful, or acceptable, for the specifications to be met,in a particular field installation, a 100 in wave guide is constructedand installed in the manner schematically indicated in FIG. 5.

In this case, a number cement blocks of 4 X 8 X 16 inches schematicallyindicated in FIG. at 27 is arranged on a pair of 2 X 4 inch constructionlumber pieces which in turn are supported on a number of stakes 30inserted into the ground and supporting pieces 28, 29 attached inotherwise well known manner by nails or screws (not shown). The guide isnow positioned on concrete slabs 27, as schematically indicated inFlG.5,at 31.

Simultaneously, guide terminations for connecting the guide to a 50 Ohmcoaxial cable are established, and also various coupling methods areinvestigated.

In a final test series, the transmission characteristics for variouspositions of the guide are measured.

Finally a carriage is provided which can be moved along the guide andprovided with a pickup as indicated in FIG. 6, in order to demonstratethe operation of the system.

FIG. 6 illustrates such as system, in which concrete slabs, woodensupports and stakes are again indicated at 27, 28, 29 and 30,respectively. In this modification,

dipole attached at 39, serving as pickup or coupling for the waveemerging from the waveguide which is arranged, supported on slabs 27, asschematically indicated at 40.

In this way, and as a result of the inherently simple construction ofthe waveguide, practical tests effectively simulating actual fieldconditions, can beperformed, as an additional feature of the invention.

While the invention has been shown and described, with specificmechanical and electrical parts and connections, it is not limitedthereto but may be applied in any other appropriate mariner, within theskill of the expert in this field, without departing from the scope andthe spirit of this disclosure.

I claim:

1. In a vehicle signal system wherein a stationary transmission line isdeployed adjacent the path of the vehicular travel, said transmissionline comprising a substantially square waveguide open at one end andclosed at the other end to define a cavity, a longitudinal conductorcentrally arranged in said cavity, said conductor being coated with adielectric coating substantially smaller than its diameter and a pair offlared sections extending at an angle from said open end of the cavityto permit the field formed in the waveguide to emerge from the flaredend to the outside path of the vehicular travel.

2. System according to claim 1, wherein said angle is about 30.

3. System according to claim 1, wherein the space between said flaredsections has height dimensions of the order of a fraction of operatingwave length, and dimensions perpendicular thereto of the order of halfof said height dimensions.

4. System according to claim 1, wherein the space between conductor andcavity is filled with a dielectric foam supporting said conductor in acentral position with respect thereto, and extending to the spacebetween said flared sections; said dielectric at said flared sectionsbeing coated with a weather resisting but wave transmissive coating.

5. System according to claim 1, wherein the height dimensions of thespace between said flared sections correspond to the order of about 20percent of operat ing wave length, and the dimensions perpendicularthereto correspond to the order of about 10 percent of operating wavelength; and wherein the diameter of said longitudinal conductorcorresponds to about 2 percent of operating wave length; said conductorbeing coated with a dielectric to a total diameter of about 3 percent ofoperating wave length.

6. System according to claim 1, comprising a pickup arranged outside ofsaid waveguide near its open end, in the form of a dipole extending intoa plane substantially perpendicular to the longitudinal axis of thespace between said flared sections.

7. System according to claim 1, wherein the maximum width of the spacebetween said flared sections at its open end is about twice of that atits closed end.

8. System according to claim 1, wherein the height of the space betweensaid flared sections is larger than that of the cavity.

1. In a vehicle signal system wherein a stationary transmission line isdeployed adjacent the path of the vehicular travel, said transmissionline comprising a substantially square waveguide open at one end andclosed at the other end to define a cavity, a longitudinal conductorcentrally arranged in said cavity, said conductor being coated with adielectric coating substantially smAller than its diameter and a pair offlared sections extending at an angle from said open end of the cavityto permit the field formed in the waveguide to emerge from the flaredend to the outside path of the vehicular travel.
 2. System according toclaim 1, wherein said angle is about 30*.
 3. System according to claim1, wherein the space between said flared sections has height dimensionsof the order of a fraction of operating wave length, and dimensionsperpendicular thereto of the order of half of said height dimensions. 4.System according to claim 1, wherein the space between conductor andcavity is filled with a dielectric foam supporting said conductor in acentral position with respect thereto, and extending to the spacebetween said flared sections; said dielectric at said flared sectionsbeing coated with a weather resisting but wave transmissive coating. 5.System according to claim 1, wherein the height dimensions of the spacebetween said flared sections correspond to the order of about 20 percentof operating wave length, and the dimensions perpendicular theretocorrespond to the order of about 10 percent of operating wave length;and wherein the diameter of said longitudinal conductor corresponds toabout 2 percent of operating wave length; said conductor being coatedwith a dielectric to a total diameter of about 3 percent of operatingwave length.
 6. System according to claim 1, comprising a pickuparranged outside of said waveguide near its open end, in the form of adipole extending into a plane substantially perpendicular to thelongitudinal axis of the space between said flared sections.
 7. Systemaccording to claim 1, wherein the maximum width of the space betweensaid flared sections at its open end is about twice of that at itsclosed end.
 8. System according to claim 1, wherein the height of thespace between said flared sections is larger than that of the cavity.